Human bladder tissue removed at surgery will be heterotransplanted subcutaneously into nude mice (NIH Swiss and BALB/c) and allowed to grow in that in vivo system for short periods. The human tumor cells will grow as solid tumors and retain both genetic and cell surface immunochemical characteristics which were present in the human host. Tumors will increase in mass 20-30-fold so that the isolation and identification of tumor-associated antigens from the tumor cell membranes can be accomplished. The extracted membrane proteins will be separated and chemically characterized by isoelectric focusing and polyacrylamide gel electrophoresis (PAGE). Immunological identification of separated proteins will be by migration of the acrylamide-separated proteins into agarose containing antihuman bladder sera and by radioimmunoassay (RIA) against heterologous antisera. Sera from patients with established bladder carcinoma will be tested for humoral responses to tumor-associated antigens and will be assessed both by cytotoxicity assays using short-term cultures of tumor cells removed from mice and by RIA analyses. Such studies should lead to the isolation of antigens which would thus be clinically useful in developing assays for early diagnosis of human bladder cancer. The system should provide an understanding of the relationships between tumor growth and immune response.